| 摘要 |
PURPOSE:To obtain a sintered body having a prescribed microstructure, superior thermal shock resistance, prescribed heat conductivity and strength by mixing powdery starting materials having the same prescribed purity and alpha-silicon nitride content but different average particle sizes in a prescribed ratio and firing a molded body of the mixture under prescribed conditions. CONSTITUTION:Silicon nitride powder of 0.1-0.5mum average grain size (D1) as starting material (1) and silicon nitride powder of prepd. so that the ratio of D2 to D1 is regulated to 2-6. Both the powders have >=99wt.% purity and >=95wt.% alpha-silicon nitride content. A mixture of 20-60wt.% of the starting material 1 with 80-40wt.% of the starting material 2 is blended with a sintering aid, molded and fired at 1,800-1,900 deg.C under pressure to obtain a sintered body having a microstructure contg. 20-50% grains of >=10mum length and 20-50% grains of <=3mum length. This sintered body has 0.13-0.16Cal/cm.sec. deg.C heat conductivity and >=800 MPa bending strength at four points. |
